It's a revolutionary invention for European snowboarding, but we almost miss it. Ripping through a foot of soft snow at the edge of a blue piste on our first morning in the French resort of Avoriaz, we are halfway back to the chairlift when I glance over my shoulder and spot something through the trees. A skinny sapling has been bent over and tethered to the ground with a piece of rope to create a wooden rainbow arc. We have found the Stash.

Every self-respecting winter resort on the planet has a freestyle terrain park, where boarders and - increasingly - skiers can hit jumps, ride metal rails or master the half pipe. But regardless of how well they are constructed, how creative the stunts or how captivating the scenery, nobody could say they were beautiful.

Building a conventional park usually involves adopting what can only be described as a scorched-earth policy. All signs of nature are flattened. In their place, tons of snow are bulldozed into line after line of immaculately groomed kickers. This may make for spectacular tricks but it does about as much for the mountain's looks as a botched nose job.

The Stash, which opened in Avoriaz this month, is different, proof that man-made is not the only way. Devised by Jake Burton - one of the first snowboard manufacturers, often credited with inventing the sport and whose eponymous company is the largest and most influential board brand on the planet - the concept is simple: take freestyle back to its roots in the trees and let the natural terrain provide the hits. It is like breaking out of the battery farm and going organic.

Standing at the top of the park a few days after it opened, the differences are immediately apparent. We are looking at a natural run through the trees of the Lindarets area. Lovely, but hardly groundbreaking. The clever bit is that it has been subtly sprinkled with rails, logs and wallrides built from local wood and designed to enhance rather than replace the existing terrain. No monster kickers, no metal rails, no pumping sound system. Just ungroomed snow and lots of wood.

We start on the main route: a long, low log rail opens proceedings, then we get air off various jumps and slide along a couple of wobbly "rainbow" logs. We crash every time, but it doesn't matter. The wood feels far more forgiving than a metal rail, the knots rippling pleasingly under the boards as we slide over, and the snow is soft anyway.

There are plenty of easy flat log rails and small jumps for those wanting to build confidence, then at the bottom of the park there is what is destined to become the Stash's signature feature - a huge stunt that involves popping up on to a large picnic table, sliding 10ft along the inclined top and then dropping several feet off the end on to a steep run-out. This is one to practise when the landing is powder. From there it's a final blast down to the lifts.

And that is just the obvious line down. It is only when we survey the park as we ride back up on the chairlift that we spot how many other features are peeking out from the branches all over the slope. This is a masterpiece of low-impact, sympathetic design.

It is also the only one of its kind in Europe (there's already a Stash, owned by the same company, at Northstar in California, and another is due to open in New Zealand) and it's no accident that Burton chose Avoriaz. The resort - part of the Portes du Soleil area, which straddles the French-Swiss border and claims to be the largest linked lift system in the world - was one of the first in Europe to embrace snowboarding and now has some of the continent's best freestyle set-ups. But it also has a long record of innovation on the environment.

Avoriaz has been car-free, ride-in ride-out since it was built in the early 1960s. Its wood-clad apartment blocks are designed to blend into the surrounding cliffs. And there are some hidden touches of genius, like the devices on the roofs that allow a thick layer of snow to build up and act as natural heat insulation.

The Stash takes that sort of innovation into boarding. Burton and the Avoriaz authorities believe they have created a blueprint for a more sustainable, ecologically aware style of piste design that takes the best of freestyle and freeride and combines them in a way that has minimal impact on the mountain. They have created a park for the planet, and it works.

· EasyJet (easyjet.com) flies from the UK to Geneva, and from there it's a 90-minute transfer to Avoriaz. Rude Chalets (0870 0687030, rudechalets.com) runs four self-catering apartments in Avoriaz, and two catered chalets down the valley in Morzine. Prices from £429-£999 per week for up to four people sharing. Further information: avoriaz.com, thestash.com.